ANORECTAL DISORDERS
  • Source: Gastroenterology (Accepted 13 January 2026)
  • Topic: Diagnostic Criteria, Clinical Evaluation and Management of Anorectal Disorders
  • Author(s): Rao SS, Bharucha AE, Carrington EV, Grossi U, Malcolm A, Neshatian L, Remes-Troche JM
1. Introduction and Overview
  • Anorectal disorders defined by symptoms and/or abnormal pathophysiology
  • Concepts evolving with sophisticated diagnostic tools
  • Article covers: fecal incontinence, anorectal pain, dyssynergic defecation, rectal hyposensitivity/hypersensitivity
  • Unlike other DGBI, DD and rectal sensory dysfunction require physiological testing; FI and anorectal pain require symptoms alone
2. Fecal Incontinence: Definition & Epidemiology
2.1 Diagnostic Criteria
  • Recurrent uncontrolled passage of fecal material for ≥3 months
  • Two or more episodes of uncontrolled passage required (changed from "recurrent")
  • Fecal staining of underwear included; flatus incontinence excluded
  • At least one FI episode per month on 4-week stool diary required for clinical purposes
2.2 Justification for Criteria Changes
  • Frequency: Term "recurrent" was nonspecific; 55% had <1 FI episode/month, yet even infrequent FI impairs QOL
  • Duration: Increased from 3 to 6 months due to lifestyle changes and alignment with Rome criteria
  • Research: Up to 50% have <1 FI episode/week with significant QOL impairment; threshold of 1/week may decrease study eligibility
2.3 Prevalence
  • Pooled global prevalence: 8.0% (all studies), 5.4% (Rome criteria)
  • Higher in older persons (9.3%) vs younger (4.9%)
  • Higher in women (9.1%) than men (7.4%)
2.4 Impact on Quality of Life & Psychological Features
  • FI significantly impairs QOL → restricts social activities, concerns about hygiene/odor/coping/fear/self-esteem/embarrassment/sexual relationships
  • Anxiety and depression associated with more severe FI symptoms and QOL impairment
  • More overlapping DGBI → worse outcomes
  • FI mixed with constipation → lower QOL than isolated FI
3. Fecal Incontinence: Risk Factors & Pathophysiology
3.1 Risk Factors & Etiology
  • Demographics: Age, female sex
  • Obstetric trauma: OASI during vaginal/instrument-assisted delivery → leading cause of sphincter trauma
  • Other: Diarrhea, cholecystectomy, diabetes, neurological/inflammatory diseases
  • Age-related: Muscle decline + emerging risk factors explain FI decades after vaginal delivery
  • Contributory: Smoking (EAS atrophy), obesity, structural disorders (rectocele, rectal intussusception)
  • Surgical: Anorectal surgery for hemorrhoids/fissures/fistula/cancer can damage sphincters
  • Other causes: Proctitis, fecal impaction with overflow diarrhea (impairs compliance)
3.2 Pathophysiological Factors
  • Continence mechanisms: IAS and EAS function, puborectalis, anorectal neurophysiology (pudendal/levator ani nerves, inferior hypogastric plexus, pelvic splanchnic nerves), recto-anal sensation, rectal compliance
  • IAS dysfunction: Decreased resting pressure from sphincter defects/thinning/neurological injury; common in idiopathic FI and scleroderma
  • EAS damage: Neuropathy, myopathy, decreased cortico-spinal input → reduced squeeze pressure
  • Levator ani: Contributes via flap-valve effect; anal cushions + sphincter tone provide closure
  • Perineal descent: Excessive → obtuse anorectal angle → impairs flap valve mechanism
3.3 Rectal Sensory & Compliance Factors
  • Up to 1/3 of FI patients have normal sphincter pressures; many have concurrent constipation or pelvic organ prolapse
  • Rectal hyposensitivity → reduced urge sensation, fecal retention, leakage before EAS contraction
  • Rectal hypersensitivity + reduced compliance → urgency
  • Rectal capacity reduced in women with FI → associated with urgency
3.4 Anal Sampling & Other Factors
  • Anal sphincter relaxation during rectal distention allows sampling to discriminate gas/liquid/stool
  • FI patients exhibit fewer sampling responses and reduced anal sensation → deprived of sensory feedback
  • Impaired rectosigmoid brake may predispose to FI
3.5 Psychological Factors
  • FI can occur during periods of stress
  • Anxiety and depression common; concurrent DGBI worsens severity and psychological distress → gut-brain axis dysfunction contributes
4. Fecal Incontinence: Clinical Evaluation
4.1 History Taking
  • Patients may not volunteer FI → ask directly
  • Bowel questionnaires useful but limited by recall bias
  • Prospective stool diaries or digital apps with pictorial scales improve accuracy
  • Assess: predisposing conditions, FI severity (type: solid/liquid/gas, quantity, frequency), awareness of urge prior to incontinence
  • Definitions: Staining = leakage 1-2 tablespoons; Soiling = more extensive leakage
  • Assess timing: after meals, BMs, exercise, or night → provides etiologic clues
4.2 Symptom-Based Mechanisms
  • Solid stool incontinence → more severe sphincter weakness than liquid alone
  • Nocturnal incontinence → uncommon, often reflects IAS dysfunction (diabetes, scleroderma)
  • Urge incontinence: Strong desire to defecate prior to leakage → associated with reduced squeeze pressure/duration, reduced rectal capacity, rectal hypersensitivity
  • Passive incontinence: Without awareness → often associated with lower resting pressure
4.3 Physical Examination
  • Abdominal and neurological examination + meticulous DRE required
4.4 Diagnostic Testing Overview
Test Purpose
Endoscopy Colorectal assessment, biopsies for microscopic colitis based on symptom profile/age/cancer risk
Anorectal Manometry (ARM) Assess continence/defecation mechanisms: sphincter/puborectalis function, recto-anal reflexes, rectal sensorimotor functions
Anal Ultrasound (AUS) Depict IAS (homogeneous hypoechoic ring) and EAS (mixed echogenicity); identify thinning/defects; 3-D AUS measures length/volume, detects atrophy
Defecography Identify excessive perineal descent, rectocele, enterocele, rectal intussusception/prolapse
Pelvic MRI Visualize sphincter structure, global pelvic floor motion without radiation; dynamic imaging at rest/squeeze/Valsalva/evacuation
4.5 Neurophysiology Tests
  • Pudendal Nerve Terminal Motor Latency (PNTML): Measures latency after intrarectal stimulation; prolonged = neuropathy; infrequently performed due to methodological limitations
  • Electromyography (EMG): Surface, needle, single-fiber methodologies; findings: normal, neurogenic, muscle injury, nonspecific
  • Sensory Testing: Anal sensation tested via electrical/thermal stimulation (unclear utility); rectal sensation evaluated by balloon distension during ARM or barostat
  • Translumbosacral Anorectal Magnetic Stimulation (TAMS): Novel test measuring MEP latencies after magnetic stimulation of lumbar/sacral plexus; superior to PNTML; 50% show lumbar and sacral plexus neuropathy; afferent cortico-anorectal evoked potentials prolonged in FI
5. Fecal Incontinence: Treatment
5.1 Dietary & Pharmacological Interventions
  • Goal: Optimize stool form, restore normal bowel habit (especially with loose stools)
  • Dietary trials: Low lactose or low FODMAP diet, psyllium (not gum arabic/carboxymethylcellulose) → improved FI vs placebo
  • Antidiarrheals: Loperamide/diphenoxylate-atropine improve stool consistency; loperamide also increases IAS tone
  • Amitriptyline: May improve FI via anticholinergic effects
  • Bile acid sequestration: Cholestyramine benefits diarrhea + FI
  • Clonidine: RCT showed improvement in stool form, decreased FI episodes when combined with colesevelam (not placebo alone)
5.2 Transanal Therapies
  • Suppositories (glycerine, bisacodyl), low volume enemas (water/osmotic), irrigation → useful in patients with abnormal evacuation
  • Elderly regimen: Lactulose 10 mL BID + weekly enemas improved FI
  • Transanal irrigation (low/high volume): RCTs support efficacy in neurogenic bowel, spina bifida, anterior resection syndrome; improved FI severity, constipation, bowel satisfaction; >1/3 discontinued within year due to poor satisfaction/side effects
  • Anal plug devices: One pivotal study: 77% of 73 completers, 62% of 91 ITT participants achieved ≥50% reduction in FI frequency
  • Vaginal bowel control device (FDA-approved): Inflatable balloon compresses rectum; 65/110 women successfully fitted, 79% achieved ≥50% reduction at 1 month
  • Anal insert device (FDA-approved): Safe, well-tolerated; >75% and 54% reported 50% and 75% reduction in moderate/full BM FI
5.3 Biofeedback Therapy (BT)
  • Uses operant conditioning/instrumental learning + Kegel exercises
  • Teaches patients to selectively contract EAS and puborectalis → improve strength/duration of anal squeeze, correct dyssynergia
  • Feedback via visual tracings of balloon volume and/or anorectal pressure
  • Reinforced by therapist + sensory perception with progressively smaller
5.4 Surgical Approaches
  • Consider for patients unresponsive to optimal medical and behavioral therapy
  • Available options range from minimally invasive neuromodulation to reconstructive approaches
  • High quality evidence of long-term efficacy is limited
5.4.1 Neuromodulation and Minimally Invasive Treatment Approaches
Sacral Nerve Stimulation (SNS)
  • Performed in 2 stages; permanent implantation contingent on response to 2–4 week test period
  • Pivotal open label US multicenter study: 90% of 120 patients received permanent stimulation
  • At 5 years, 76/120 (63%) evaluated; 36% achieved complete continence, 89% deemed therapeutic success
  • Another 5-year follow-up (n=101, ITT analysis): 42.6% had favorable outcome
  • Predictors of success: younger age, urge FI, 6-month response
  • Cross-over study (n=27): 90% reduction in FI episodes during SNS vs 76% without, but significant attrition bias
  • Limitation: No high-quality multicenter sham-controlled RCT has confirmed efficacy; mechanism(s) uncertain
  • Sham-controlled trials show clinically meaningful improvement with sham stimulation
Percutaneous Tibial Nerve Stimulation (PTNS)
  • Not shown significant benefit over sham in multiple RCTs, including a large trial (CONFIDeNT)
  • May be combined with biofeedback in patients with coexistent FI and obstructive defecation
Translumbosacral Neuromodulation Therapy (TNT)
  • Delivers repetitive magnetic stimulations to lumbar and sacral plexus nerves
  • Improves nerve conduction through neuroplasticity
  • Dose-ranging RCT (1 vs 5 vs 15 Hz): 1 Hz frequency was superior with 91% responders (>50% reduction in FI episodes)
  • Anal neuropathy, squeeze pressure, rectal capacity, and QOL improved significantly
  • Good correlation between improved neuropathy and FI responders → suggests TNT works via neuromodulation
  • Recent sham-controlled study further confirmed TNT's efficacy
Sphincter Bulking Therapies
  • Biocompatible materials injected into submucosal or intersphincteric space to augment anal barrier
  • 5 RCTs evaluated 10 different materials in 382 patients
  • Pivotal trial (n=206): Dextranomer in stabilized hyaluronic acid (NASHA Dx) achieved 52% response (50% reduction in FI episodes) vs 31% sham (NNT =4.4)
  • Adverse events mostly mild (proctalgia, bleeding); rare abscesses
  • Sustained benefit up to 3 years suggested; improvement in QoL not significant; physiological/imaging data lacking
  • At 2 years, NASHA Dx outcomes comparable to BT
  • Best responders: shorter FI duration, obstetric causes, no prior therapy
  • Recent large multicenter RCT: dextranomer and BT had ~29% responder rate
SphinKeeper™ Implants
  • Implants 10 self-expandable polyacrylonitrile prostheses (20 mm × 1.8 mm) into intersphincteric space
  • Adverse events: prosthetic displacement (14%), anorectal pain (71%)
  • Multicenter retrospective cohort study with 3-year follow-up confirmed safety, efficacy, QOL benefits in refractory FI
  • Long-term outcomes lacking
Intrarectal Botulinum Toxin
  • Randomized placebo-controlled study showed reduction in frequency of FI episodes and urgency episodes
  • Deserves further evaluation, especially for urge FI
5.4.2 Direct Reconstructive Approaches
  • Historically, most surgery directed toward repair of anal sphincter defects
  • Overlapping anterior sphincteroplasty: Up to 60–85% improved in short-term studies
  • Long-term results disappointing: Failure rates of ~50% after 40–60 months
  • Recent innovations: Autologous skeletal muscle derived cell implantation, bioengineered IAS from autologous cells
5.4.3 Ostomy
  • Colostomy remains last resort for severe FI
  • Improves QOL
6. Anorectal Pain Disorders: Overview
6.1 Classification
  • Three anorectal pain syndromes described: Levator ani syndrome (LAS), unexplained anorectal pain, proctalgia fugax
  • Distinguished based on pain duration and presence/absence of levator ani tenderness during DRE
7. Levator Ani Syndrome (LAS) & Unexplained Anorectal Pain
7.1 Definition
  • LAS: Vague, dull ache or pressure sensation in rectum; worse with sitting than standing/lying
  • DRE reveals tenderness on palpation of levator ani muscles
  • Recent study: DRE reproduced pain in one or more anal quadrants with similar pain severity (not just left-sided)
  • Unexplained anorectal pain: Same symptom criteria as LAS but no tenderness during traction on puborectalis
7.2 Diagnostic Criteria for LAS

Must include all:

1. Chronic or recurrent anorectal pain

2. Episodes last 30 minutes or longer

3. Tenderness during traction on puborectalis

4. Exclusion of other causes: anal fissure, thrombosed hemorrhoids, malignancy, infectious/inflammatory causes (IBD, perianal abscess/fistula), prostatitis, coccygodynia, gynecological causes

7.3 Diagnostic Criteria for Unexplained Anorectal Pain
  • Symptom criteria for LAS but no tenderness during traction on puborectalis muscle
7.4 Justification for Criteria Changes
  • Order of other conditions changed to be consistent with frequency
  • "Structural alterations" replaced with "disorders"
  • "Posterior traction" removed since traction at other quadrants also evokes pain
  • Term "Functional" removed
7.5 Epidemiology
  • Prevalence of anorectal pain (all causes): 11.6% in community; similar across genders
  • LAS prevalence: 1.1% (internet survey), 0.7% (household survey) in Rome Foundation Global Epidemiology Study
7.6 Pathophysiology
Physiological Factors
  • Hypothesis: Excessive pelvic floor contraction → elevated resting pressures
  • RCT of 157 patients with chronic anorectal pain (Rome II criteria): 85% of patients with levator tenderness had dyssynergia with manometry but not constipation
  • Reversal with biofeedback strongly predicted symptom relief → implies dyssynergia as mechanism
  • 3-D AUS showed more contracted puborectalis at rest and straining in chronic proctalgia vs healthy controls
  • 34% of LAS patients met criteria for DD
  • Impaired anorectal afferent pathways and high prevalence of anal lumbar/sacral plexus neuropathy suggest neurophysiological dysfunction causes pain
Psychological Factors
  • Associated with psychological disturbances
  • Case-control study: Women with history of sexual abuse had higher prevalence of LAS and proctalgia fugax
7.7 Clinical Evaluation
  • Diagnosis relies on characteristic episodes of anorectal pain with levator muscle tenderness on palpation
  • Exclude fissure; anoscopy/sigmoidoscopy may identify mucosal disease
  • If perianal disease suspected (abscess/fistula): cross-sectional imaging
  • Consider: anorectal manometry, defecography, TAMS test
  • TAMS findings: Prolonged MEP latencies indicating lumbar/sacral plexus neuropathy; weak anal sphincters, features of DD with prolonged balloon expulsion time
7.8 Treatment
  • RCT findings: 87% of patients with levator tenderness reported adequate pain relief after BT vs 45% after electrical stimulation vs 22% after massage
  • Patients without tenderness did not benefit from any therapy
  • Electrogalvanic stimulation considered if BT unavailable
  • Retrospective studies suggested improvement after intra-anal or intra-levator botulinum A toxin injection; one RCT found no benefit over placebo
  • Open label study of TNT: significant improvement in anorectal pain and lumbosacral neuropathy
  • Ineffective: muscle relaxants, diazepam, SNS, sitz baths, radiofrequency, pudendal infiltration, transgluteal decompression, TENS, laparoscopic decompression
8. Proctalgia Fugax
8.1 Definition
  • Sudden, severe pain in rectal area lasting seconds to minutes, then disappearing completely
  • Attacks infrequent: typically <5 times/year in 51% of patients
  • Pain described as cramping, gnawing, aching, or stabbing; ranges from uncomfortable to unbearable
  • Can happen anytime; 50% report nocturnal attacks interrupting activities
8.2 Diagnostic Criteria

Must include all:

1. Recurrent episodes of pain localized to anorectum, unrelated to defecation

2. Episodes last from seconds to minutes

3. No anorectal pain between episodes

4. Exclusion of other causes: anal fissure, thrombosed hemorrhoids, malignancy, infectious/inflammatory causes (IBD, perianal abscess/fistula), prostatitis, coccygodynia, major structural disorders of pelvic floor

8.3 Epidemiology
  • Prevalence: 5.6% (internet survey), 1.5% (household survey)
  • Questionnaire-based → other anorectal disorders not excluded
  • 1.3-fold more common in women; occurs in children
  • Few patients seek healthcare, but can be disabling
8.4 Pathophysiology
Physiological Factors
  • Abnormal smooth muscle contractions may be responsible for pain
  • Hypertrophy of IAS reported in hereditary form of proctalgia fugax
Psychological Factors
8.5 Clinical Evaluation
  • Diagnosis based on characteristic symptoms and exclusion of anorectal and pelvic pathophysiology
  • Chronic pelvic pain pathologies (endometriosis in women, chronic prostatitis in men) may mimic symptoms
8.6 Treatment
  • Described as "harmless, unpleasant, and incurable"
  • Reassurance often sufficient; frequent/severe attacks may require therapy
  • RCT: Inhaled salbutamol shortened duration of severe and prolonged attacks vs placebo
  • Other options suggested (no comparative studies): clonidine, amylnitrite, nitroglycerine, neuromodulators, behavioral therapies
9. Dyssynergic Defecation (DD)
9.1 Definition
  • Characterized by paradoxical contraction or inadequate relaxation of pelvic floor muscles and/or inadequate propulsive forces during attempted defecation
  • Symptoms alone do not distinguish DD from other evacuation disorders; some asymptomatic controls show dyssynergia pattern
  • Diagnosis requires constipation symptoms + abnormal anorectal tests
  • Term "DD" preferred over "pelvic floor dyssynergia" since most DD patients report only difficult defecation, not urinary or sexual dysfunction
9.2 Epidemiology
  • Population prevalence uncertain (requires physiologic testing)
  • Of 11,112 constipated patients in community: 516 had undergone anal manometry; 245 (47%) had DD (209 women, 36 men)
  • Age-adjusted incidence per 100,000 person-years: 31.8 [95% CI, 27.4–36.1] in women vs 6.6 [95% CI, 4.4–8.9] in men (p<0.0001)
  • Before diagnosis: ~30% had IBS, 48% had psychiatric diagnosis, 18% had abuse history, 21% reported urinary and/or fecal incontinence
  • At tertiary centers: DD prevalence among constipated patients ranges 20% to 81%
9.3 Diagnostic Criteria for DD

Must include all:

1. One or more symptoms of difficult evacuation (excessive straining, digital maneuvers to evacuate, sensation of anorectal blockage, feeling of incomplete evacuation) with at least 25% of BMs; may satisfy criteria for chronic constipation or IBS

2. During attempted defecation, impaired evacuation demonstrated by any one of:

  • Reduced rectoanal pressure gradient or abnormal anorectal evacuation pattern on ARM
  • Abnormal balloon expulsion test (BET)
  • Impaired rectal evacuation with defecography
9.4 Justification for Changes in Diagnostic Criteria
  • Term "functional" removed
  • "Defecation disorders" is broad (includes functional and structural like rectal prolapse); DD more specific
  • Removal of Type 3 dyssynergia and EMG (latter rarely used clinically)
  • Symptom criteria: Many constipated patients report difficult evacuation but don't satisfy Rome IV functional constipation or IBS; Rome V allows diagnosis if ≥1 symptom occurs >25% of time and physiology criteria fulfilled
  • Rome IV required abnormalities in ≥2 of 3 modalities (balloon expulsion, manometry, imaging) but concordance limited
  • Rome V proposal: Any one abnormal finding sufficient to diagnose DD in patients with difficult evacuation (prolonged BET, reduced gradient, abnormal pattern, or reduced rectal evacuation by defecography)
  • Rationale: Abnormal BET and gradient are 81% and 86% specific, respectively, for predicting reduced rectal evacuation; avoids unnecessary tests with radiation exposure
  • Classification: Patients with one abnormal test = probable DD; ≥2 abnormal tests = definite DD
  • Rectoanal Gradient (RAG): Best manometry measure of abnormal evacuation; reduced gradient reflects inadequate rectal propulsive force and/or impaired anal relaxation
  • Subclassification removed: Inadequate propulsion and paradoxical contraction subtypes don't reliably discriminate healthy from DD patients or predict BT response
9.5 Pathophysiology
Physiological Factors
  • DD is an acquired behavioral disorder where patients "unlearn" normal defecation; can be relearned through BT
  • Normal defecation: Increased rectal pressure coordinated with relaxation and opening of anal canal and perineal descent
  • Cardinal abnormality in DD: Incoordination characterized by inadequate rectal propulsive force and/or impaired relaxation or paradoxical contraction of EAS/puborectalis
  • Earlier studies with isolated left lateral and seated manometry: patients had inadequate propulsive force and/or impaired pelvic relaxation
  • Proctomanometry (pressures and evacuation assessed simultaneously): 78% of nonevacuators had global anorectal dysfunction (reduced rectal pressures, pelvic floor relaxation, puborectalis relaxation during defecation)
  • Volitional control of defecation requires activation of multiple brain regions
  • Functional MRI shows altered activation in several brain regions (primary/supplementary motor, somatosensory cortices, emotional arousal networks: hippocampus and prefrontal cortex) during defecation in DD vs healthy controls
  • Abnormal colonic motor function may also contribute
Psychological Factors
  • Withholding behavior in childhood → DD persisting into adulthood → cycle of hard stools, difficult/painful defecation, stool retention
  • DD patients report more anxiety, depression, paranoid ideation, hostility, obsessive-compulsive traits than those with slow transit constipation
  • Psychological distress adversely affects biofeedback outcomes
  • 85% of DD patients have ≥1 additional DGBI (e.g., 36% have rectal pain, 41% functional dyspepsia) → associated with poorer mental health, QOL, social functioning
  • Uncontrolled studies: 22% of women with DD reported sexual abuse; in these patients, rectal fullness may trigger traumatic memories and involuntary pelvic floor contraction
9.6 Clinical Evaluation
Key Symptoms
  • Excessive straining, feeling of incomplete evacuation, use of digital maneuvers, infrequent BMs (<3/week), prolonged time on toilet, sensation of anorectal blockage during defecation
  • DRE findings critical to diagnosis
  • Bowel diaries overcome recall bias inherent to questionnaires and interviews
Diagnostic Testing for Suspected Defecation Disorders
  • Recommended in patients with suspected DD or laxative-refractory constipation
  • ARM, BET, magnetic resonance or fluoroscopic defecography, colonic transit provide complementary information
9.7 Balloon Expulsion Test (BET)
  • Patient attempts to expel water-filled rectal balloon (50 ml or inflated until defecatory desire) in privacy, seated on commode
  • Normal expulsion times: 20 seconds to 2 minutes; 1-minute cutoff recommended
  • Results highly reproducible (90% of individuals across days)
  • Useful as screening test; doesn't reveal DD pathophysiology
  • May be normal in some patients with constipation and features of DD by defecography or manometry
Rectal Expulsion Device (RED)
  • Mimics Bristol 4 stool
  • In 52 patients, RED in left lateral position (abnormal defined as <5 seconds or >120 seconds) predicted response to pelvic floor physical therapy
  • Seated RED enhanced ability to predict response; unclear if included biofeedback techniques
9.8 Anorectal Manometry (ARM)
  • Intra-rectal and anal pressures measured during attempted defecation
  • Earlier studies used water-perfused or solid-state manometry catheters; newer options include HR-ARM (interpolates pressures between multiple circumferential sensors) and air-charged, disposable catheters
  • Normal pattern: Increased intrarectal pressure associated with anal relaxation
Historical Patterns (No longer subclassified)
  • Type I: Adequate propulsion (≥45 mmHg) with paradoxical anal contraction
  • Type II: Inadequate propulsion (<45 mmHg) with paradoxical contraction or insufficient relaxation
  • Type III: Adequate propulsion (≥45 mmHg) with absent/insufficient anal relaxation (<20%)
  • Type IV: Inadequate propulsion (<45 mmHg) with inadequate relaxation (<20%)
Current Understanding
  • Controlled study: 87% of healthy participants had "abnormal" patterns suggestive of DD (based on older normal values assessed with non-HRM in seated position)
  • Normal values differ considerably between HRM and non-HRM catheters, and among different HRM catheters
  • Even among healthy persons with normal BET, 10–90th percentile range for RAG during LL HR-ARM is –70 to 12 mmHg in women and –128 to 1 mmHg in men
  • RAG abnormal only when below lower limit of normal
  • When interpreted relative to sex- and age-appropriate normal values, abnormal RAG (Manoscan™ catheter) is 36% sensitive and 85% specific for predicting prolonged BET
  • Lower RAG and prolonged BET independently associated with reduced evacuation
  • Probability of reduced rectal evacuation: 14% when both measures normal, 45% when either abnormal, 75% when both abnormal
Technical Considerations
  • Performed generally in left lateral position; pressures and RAG greater in seated than left lateral position
  • Seated HRM more useful than left lateral for distinguishing healthy individuals from DD patients
  • Ideally, attempted defecation performed in more physiological seated position (challenging due to catheter displacement)
  • Anorectal pressures and defecography can now be measured concurrently via fluoroscopy or MRI
  • These studies disclose 2 phases: preparation and evacuation; during preparatory phase, rectal and anal pressures increase early and concurrently (even in healthy persons); thereafter anorectal junction descends indicating pelvic floor relaxation; once rectal pressure exceeds anal pressure, positive RAG established opening anal canal enabling evacuation
  • MRI discloses